A Sliding Mode Control (SMC) strategy for Active Queue Management (AQM) routers supporting Transmission Control Protocol (TCP) data transfer is suggested. It is based on the input-delayed model of TCP behaviour developed in Misra et al. [2000], which is reduced to a delay-free model by means of Artstein's transformation Artstein [1982]. The suggested feedback-control scheme is proved to be stable under the adopted variable structure strategy and ensures robustness against disturbances and unmodelled dynamics. The performance of the new AQM algorithm compares favourably with that afforded by alternative AQM techniques.
